auto-dimming navigation screen problem

[Q70sGuy]

I have a US spec 2012 FX35 with the base audio system and navigation. I'm not the first owner but since I have had the car I realized something was wrong with the auto-dimming function of the navigation screen. When on 'auto' mode, it is always set to night.

I am well aware of the function and how it works, and I have tried every combination with the headlight switch to get it to work. I finally got a scanner capable of reading live data from individual modules and have confirmed that the BCM correctly interprets the headlight switch on-off-auto, but the AV system module is stuck on Illum. Signal ON. Its a bit complicated to understand but from reading the FSM it sounds like the AV control module is getting illumination signal from the tail lamp relay (FSM INL-89 in the 2010 FX). But my tail lamps turn on... so is the problem between the tail lamp relay, the ignition switch which sits between them, and the module? I suppose I can easily check for 12v at the plug behind the AV control module and figure that out, but before i tear apart the interior again I would like some opinions?

the diagrams on the site are only available for the 2010 model but I assume theyre the same for 2012.
Has anyone encountered this issue and found a solution?

[VStar650CL]

That setup is true of most Nissan/Infiniti AV Units before about '17, the AV dimming isn't controlled directly by the BCM but indirectly by the interior backlighting. If the latter works then the AV dimming should work as well. BUT, most of them also have a day/night button which will override the lighting input when "night" is selected. Make sure your button simply isn't set on night.

[VStar650CL]

[Q70sGuy]

Yes that’s the thing when it’s on auto it’s always on night. The only two options are auto(night) and day. I think I’ll have no choice to just test the input wire into the control unit, but if I need to replace the control unit I imagine I need to get the one with the same exact specs as mine?

[VStar650CL]

In order for it to be stuck in night mode, the input wire would need to be a digital "high" at all times. That's pretty unlikely. On your FX, the line which feeds the AV illumination pin has bulbs on it (glove box lamp and lighter illumination). Unless maybe you replaced both of those with LED and the diode-drop is causing an issue, the bulbs should be acting as pull-down resistors when the taillight relay is off. That should provide a hard ground to the AV input. So if you measure that wire with the lights off and it reads 0V, it pretty much means your AV must have a blown input.

[Q70sGuy]

I found the correct wiring diagram and now I see what you meant! I'll investigate but doubt any bulb was replaced. Thanks for the guidance. I am just surprised I havent found anyone else with a similar issue in my searches but once I solve it I'll update this page and maybe it will be useful to others.

[Q70sGuy]

Update - I haven’t looked into this again but I noticed that my parking lamps are all on even with the combination switch on off, if the ignition is on. That explains the AV unit thinking they’re always on… because they are.

Since this is a USA FX I think that maybe they used this method for daytime running lamps (mandatory in Canada), or the relay is broken and stuck on.

Does anyone know how the dealer turns on or off DRL usually? In the service manual it seems like a simple on-off with the C3.

[VStar650CL]

According to the FSM, the '12 FX uses the fog lamps for DRL and not the parking lamps. So whatever is turning the parks on isn't a configuration issue. You can confirm whether it's electrically-related by applying the parking brake with the car idling in Park, if the DRL system is involved then applying the brake should turn off the lamps. Otherwise you have an unrelated issue, an internal problem in the IPDM or a crossed circuit in the wiring. If I was diagnosing it in the shop, I'd first interrogate the IPDM to see if the parking lamps were requested. If so, I'd interrogate the BCM to see if the combination switch had a melted diode. If not, I'd pull the park and tail fuses and see if the lights stayed on. If so I'd know the wiring had a problem, otherwise it would mean a faulty IPDM.

Note that I did once see an incident with an NV2500 where the radio was blown and back-powering the parking lamp circuit through the illumination pin. That was a one-off which I've never seen again, but since it's your radio that's misbehaving, I wouldn't rule that out.

[Q70sGuy]

I see now in the FSM - does this mean the US FX have DRL on by default?

And I just saw in the FSM that the IPDM relays aren’t actually replaceable like I dreamt they would be, So it’s a replacement if ever.

At least we’re narrowing it down now - internal IPDM issue or just wiring somewhere.

[VStar650CL]

I see now in the FSM - does this mean the US FX have DRL on by default?

I would think it's standard equipment, yes. I don't see any "option flags" in the wiring diagram, which generally means all trim levels have it. I also don't see any option in the BCM or IPDM to disable the function.

And I just saw in the FSM that the IPDM relays aren’t actually replaceable like I dreamt they would be, So it’s a replacement if ever.

Yep, that's true of most of the IPDM's after about '10. The only two exposed relays are the starter cut and I forget what the other one is. The newest ones don't have any exposed relays at all and about 50% of the fuses have been replaced by "smart FET's". Fortunately those are a lot smarter than the "smart" charging systems, but you still need to replace the IPDM when one blows.

The good news is, the IPDM on your '12 is plug-and-play. So if that turns out to be the problem, a used one is fine and there's no screwing around with configurations. Just make sure the part number matches exactly.

[Q70sGuy]

That’s good news, my scanner can’t do configuration I think. But the IPDMs on eBay are more pricey than av control units. It’s -25c (-13f) right now and the garage is full of junk so the screen will stay bright for a little while longer

[Q70sGuy]

All right , solved!

It was indeed some kind of DRL workaround that was installed. I saw a wire from the battery to a relay that then was wired into the IPDM.unplugged the battery positive and voila.
it’s still -20 so I didn’t really look into it any further.

But I have no more DRL; so I ask other members with American FX models - do you actually have daytime running lights on your fogs?

[VStar650CL]

We have a saying in the shop, "When Harry Backyard gets involved, you won't find the answer in the FSM."

Sounds like he claimed another victim. Say hi for me.

[VStar650CL]

Come to think of it, we had a Harry job just today, except Harry was a body shop who probably should have known better. It's a '25 Altima, front end damaged and the grille and fascia were replaced. No big damage and no structural parts damaged or changed. They want us to calibrate the Radar, except we can't because it throws a C1A16 (blockage) as soon as you turn it on. Then 30 seconds later the ADAS throws a C1A26-97. Weird combination, because the latter is an ABS-ADAS comm code and pretty much calls for replacing the ADAS if there aren't "U" codes with it. Very puzzling in light of the Radar, which simply shows blocked. No comm or malfunction codes at all. The Radar wiring under the front cover looks fine and nothing is unplugged. Wtf?

Then I look at the grille emblem and it looks... hmm... "off" somehow. We find another Altie on the lot and sure enough, ours doesn't look right. My compatriot pops it off and bing!, both DTC's instantly go "past" and erase. The body shop idiots used a cheap China emblem in front of the Radar which didn't have the special non-metallic chrome that allows the beam to get out. We still don't know why it caused that particular ADAS code, only some fugitive programmer in Continental's basement will ever know the answer to that. But that was the proximate cause.

The ultimate cause was a body shop who hired Harry.

[Q70sGuy]

Absolutely, the reason I suspected the DRL trickery is because I worked at Infiniti years ago and I recall seeing something being done for DRL in USA cars moving to Canada.

On my car the first owner just bought it and brought it here from day one. So this must have been going on from day 1!